const singers = [
    { name: '许嵩', num: 200 },
    { name: '周杰伦', num: 266 },
    { name: '林俊杰', num: 201 },
    { name: '陈奕迅', num: 166 },
    { name: '薛之谦', num: 233 },
]

const res = singers.fill('刘德华', 1, 3)
console.log(res);

Array.prototype.my_fill = function(value, start = 0, end) {
    end = end || this.length
    for(let i = start; i < end; i++) {
        this[i] = value
    }
    return this
}
